Method of and apparatus for making metal tubes



J. Kozlcz 1,800,023

METHOD OF' AND APPARATUS FOR MAKING METAL TUBES April 7, 1931.

Filed Jan. 10, 1927 2 sheets-sheet l HllIIlll-ll IIII 1 `lllllllllllllllllllll J. Kozlcz 1,800,023

MTHOD OF AND APPARATUS FOR MAKING METAL TUBES April 7*, 1931.

2 Sheets-Sheet 2 Filed Jan. l0, 1927 WMVEY j pr. W193i,

PATENT ori-lcs JoHANN-xozmz, or VIENNA, AUSTRIA application led January 10, 1927, Serial No. 160,181, and in Austria January 16, 1926.

invention relates to an y'improved method of and-apparatus for bending metal strips between pairs of rolls.

Arrangements for carrying out this method are already known, in which the cross-sectionalshapes ofthe lrolls are such, that the met-al strip is pressed between two rolls along its entire 'cross-sectional area, so that it is necessary to increase the pressure of the roll and to lubricate the' strip, While at the same time the Vmaterial is hardened, which is not desirable 'as it is detrimental to a uniform shaping and employment of the metal tube. One of the rolls of one or'more of the 'final pairs of rolls is formed with a central circumferental flange serving to prevent the edges ofthe strip from being forced together.

According to the present invention, thc metal strip is subjected to a pressure at both sides in the vicinity of the longitudinal edges l only between a series of pairs of rolls vof graduali varying consecutive cross-sectional shapes, t e distance between the top roll and the bottom roll of each pair of rolls, except those at or near the outlet end of the series' being smaller at the outer edges of the profiles of the rolls than in the middle thereof. Because the metal strip rests only against the top roll and is firmly pressed solely at the edges, while its middle portion lies hollow, any excessive generation of heat is prevented, so that the lubrication of the strip and the cooperating faces of the rolls can be dispensed with. Further, in the case of rusty or sealy sheet-metal being used, the rust or scale dropping ofi' during the bending opera; tion may readily drop into the hollow space remaining between the two cooperating rolls,

so that the rustl or scale cannot be pressed into 40 the roll. In the old methods this rust or scale is pressed into the surface ofith'erolls` and Y consequently the latter quickly wear oi and become untrue, so that the metal lstrips are damaged and deformed'during the passage between therolls. This drawback is still more increased inthe event of lubricated rolls, because rust or scale `adheres to ay greater extent. f

By arranging the rolls according to the 50 present invention one can employ not only raw sheet metal, but also nickel-plated or like sheet metal, which passes out of the last pair of rolls quite dry and without requiring' l any finishing work, so that the cross-sectional arca of the tube to be made is quite immaterial. Particularly square tubes can be rolled over the edge by this method. A further advantage consists in this that the pairs oi' rolls at or near the inlet end of the series will serve for the production of a number (four to five) of diii'erent profiles, for the completion of which it is necessary only to exchange from time to time the corresponding en or last pair of rolls, while the other rolls remain the same.

In the drawings Figs. 1 and 2 illustrate diagrammaticaliy an apparatus in sectional elevation and plan view respectively for carrying out the method according to the present invention.

Figs. 3, 4. 5 and 6 illustrate four successive pairs ,of rolls.

As shown in F igs. 1 and 2, the apparatus comprises' two double walls l and 2 between which are arranged'the drawing-in rollers i and F, the profiling or forming rolls A, B, C and D and the guide-rolls 9 and 10 for the band-iron or the metal strip. The two wails 1 and 2 are divided into sections, in which are arranged the roller-bearings 4 and 5 of the topand bottom rolls, the bearing of cach bottom roll resting on a support 6. The

individual sections are connected with one another Iby longitudinally extending bars iii, The roller-bearings 4 and 5 and the supports iti 6 are provided with two vertical grooves, by

.means of which they are guided on the two )lates of the double walls 1 and 2. The p eight'of the bottom roll is determinedbyA the .height of the support 6, while the top roll UU can be ad'usted by means of set screws 8.

Suitably s iaped guide-rolls 9 and 10 are arranged in any convenient manner intermedi ate the individual profiling or shaping rolls, while the drawing-in rollers E and F are U5 mounted on a bearing 11. secured to the two vdouble walls 1' and 2. The rolls are rotated by means of toothed bevel-wheels 14, which mesh with bevel-wheels 13. secured on a conimon drive shaft 12. In the illustrated em 19a bodiment, the top roll of each pair of rolls is rotated by the gear and is providedA with .l

i `a toothed wheel 15, which meshes with a toothed wheel secured to the shaft of .the corresponding bottom 4roll, so that the top rolls and thebottom rolls are rotated in opposite directions.

As shown in Figs. 3 to 6, the profile or cross-sectional shape of each pair of rolls A,

B, C and D is such, that Ithe distanceat 4theouter rim or edge p is smaller than at the middle fm so that, provided the band-iron or metal strip is of 'a uni-form thickness, the latter is pressed at the outer rim or edge only between the two rolls, while tlierremaining portion of the said strip solely rests against the top roll and does not Contact with the bottorn, roll. In order to prevent a lateral disf placement between the two rolls and to accurately adjust' the profile or crosssectional shape, the top rolls are provided with a collar b at both ends, which collar engages a correp sponding circumferential groove c ofthe bot# tom roll. 'In order to prevent a screw shaped tube-seam, the top roll D of thev pair of rolls,

' .l through which the tubev passes-"immediately before the finishing of the profile, isequipped with a central dise D', which enters the tube-'- seam and moves in the sameduring-thevfeed of thel tube. Preferably, the guide-roll 1f), lying behind the same, Y is provided @with a similar discfin order to prevent the tube from being subjected to torsion behind the lpresser roll D.

The machine operates ,in the following. manner The metal strip is 'passed by Wayv7 of the .A drawing-inrolls F to the first pair of shaping rolls A, is grasped by the rotating top Aand bottom rolls Aand is automatically fed to the next pair of rolls and so on, until the shaping isfinished by a roll disposed lbehind the roll "DQ The tube is smoothed and exactly shaped by a subsequent roll, the tube thus leaving the machine in a soft anddry condition and provided with a seam. If necessary, a welding device may be disposed behind the `last roll, to close the entire 'seam in one operation,

The central-disc D of the top rollD projects through the seam of the tube anddi-V rectly operates on the metal strip resting upon the bottom roll, so that this d-iscnot only uides the seam of the tube in a strai ht line, ut also servesas a means for holding r 1. The method of bending fa'inetalstrip in these cases the guidel and ,retaining discs` D of the correspondingshaping rolls prei vent any torsion in the produced 'tubular prism and safeguard the accurate shape of I the tube.

Also Va number offracks; of rolls may bev arranged side by side in a single-fremden that tubes of different diameters may be bent simultaneouslyl in a single operation.l

comprising passing vsaid strlp between' successive pairs ofrolls of gradually differing ,i

cross-section so as to subjectthe metal strip topressure along its longitudinal edges only, and maintaining the other portion of the metal strip out of contact with the bottom roll ofeach pair of rolls.

2. .An apparatusfor bending atmete-l strip I' comprising successively arranged pairs -of superposed shaping rolls 'of graduallydiffering Vcross-section, the. distance between,

the cooperating surfaces of said rollsjat their y outer edges being smaller than in their centerv so as to prevent contactof the metal strip withthebottom rolll means for rotating said rolls', and disk-shaped guide elements interm'ediate said-'pairs of rolls.

.3. In apparatus for bending a strip into tubular form, a pair of cooperat-in rolls be-r` tween which the strip is adapted .to e passed,

one of said rolls having a'groo've and the other having a cooperating projection eX- V tending into said groove, thecontours of the groove and the projection being such' that when the rolls are in contact; thestrip to either side of said grooveland 'said pro-f jectlon, a space eXists bet lween the strip and the' bottom .of the groove inthe :'rst men` 'tined roll.

In testimony whereof I 'aliii my signature.'

.Tenants Kozroz. 

